/*
* Copyright (c) 2006-2009 Erin Catto http://www.box2d.org
*
* This software is provided 'as-is', without any express or implied
* warranty.  In no event will the authors be held liable for any damages
* arising from the use of this software.
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/

#include <Box2D/Dynamics/Contacts/b2Contact.h>
#include <Box2D/Dynamics/Contacts/b2CircleContact.h>
#include <Box2D/Dynamics/Contacts/b2PolygonAndCircleContact.h>
#include <Box2D/Dynamics/Contacts/b2PolygonContact.h>
#include <Box2D/Dynamics/Contacts/b2EdgeAndCircleContact.h>
#include <Box2D/Dynamics/Contacts/b2EdgeAndPolygonContact.h>
#include <Box2D/Dynamics/Contacts/b2ChainAndCircleContact.h>
#include <Box2D/Dynamics/Contacts/b2ChainAndPolygonContact.h>
#include <Box2D/Dynamics/Contacts/b2ContactSolver.h>

#include <Box2D/Collision/b2Collision.h>
#include <Box2D/Collision/b2TimeOfImpact.h>
#include <Box2D/Collision/Shapes/b2Shape.h>
#include <Box2D/Common/b2BlockAllocator.h>
#include <Box2D/Dynamics/b2Body.h>
#include <Box2D/Dynamics/b2Fixture.h>
#include <Box2D/Dynamics/b2World.h>

b2ContactRegister b2Contact::s_registers[b2Shape::e_typeCount][b2Shape::e_typeCount];
bool b2Contact::s_initialized = false;

void b2Contact::InitializeRegisters()
{
    AddType(b2CircleContact::Create, b2CircleContact::Destroy, b2Shape::e_circle, b2Shape::e_circle);
    AddType(b2PolygonAndCircleContact::Create, b2PolygonAndCircleContact::Destroy, b2Shape::e_polygon, b2Shape::e_circle);
    AddType(b2PolygonContact::Create, b2PolygonContact::Destroy, b2Shape::e_polygon, b2Shape::e_polygon);
    AddType(b2EdgeAndCircleContact::Create, b2EdgeAndCircleContact::Destroy, b2Shape::e_edge, b2Shape::e_circle);
    AddType(b2EdgeAndPolygonContact::Create, b2EdgeAndPolygonContact::Destroy, b2Shape::e_edge, b2Shape::e_polygon);
    AddType(b2ChainAndCircleContact::Create, b2ChainAndCircleContact::Destroy, b2Shape::e_chain, b2Shape::e_circle);
    AddType(b2ChainAndPolygonContact::Create, b2ChainAndPolygonContact::Destroy, b2Shape::e_chain, b2Shape::e_polygon);
}

void b2Contact::AddType(b2ContactCreateFcn* createFcn, b2ContactDestroyFcn* destoryFcn,
                        b2Shape::Type type1, b2Shape::Type type2)
{
    b2Assert(0 <= type1 && type1 < b2Shape::e_typeCount);
    b2Assert(0 <= type2 && type2 < b2Shape::e_typeCount);
    
    s_registers[type1][type2].createFcn = createFcn;
    s_registers[type1][type2].destroyFcn = destoryFcn;
    s_registers[type1][type2].primary = true;

    if (type1 != type2)
    {
        s_registers[type2][type1].createFcn = createFcn;
        s_registers[type2][type1].destroyFcn = destoryFcn;
        s_registers[type2][type1].primary = false;
    }
}

b2Contact* b2Contact::Create(b2Fixture* fixtureA, int32 indexA, b2Fixture* fixtureB, int32 indexB, b2BlockAllocator* allocator)
{
    if (s_initialized == false)
    {
        InitializeRegisters();
        s_initialized = true;
    }

    b2Shape::Type type1 = fixtureA->GetType();
    b2Shape::Type type2 = fixtureB->GetType();

    b2Assert(0 <= type1 && type1 < b2Shape::e_typeCount);
    b2Assert(0 <= type2 && type2 < b2Shape::e_typeCount);
    
    b2ContactCreateFcn* createFcn = s_registers[type1][type2].createFcn;
    if (createFcn)
    {
        if (s_registers[type1][type2].primary)
        {
            return createFcn(fixtureA, indexA, fixtureB, indexB, allocator);
        }
        else
        {
            return createFcn(fixtureB, indexB, fixtureA, indexA, allocator);
        }
    }
    else
    {
        return NULL;
    }
}

void b2Contact::Destroy(b2Contact* contact, b2BlockAllocator* allocator)
{
    b2Assert(s_initialized == true);

    if (contact->m_manifold.pointCount > 0)
    {
        contact->GetFixtureA()->GetBody()->SetAwake(true);
        contact->GetFixtureB()->GetBody()->SetAwake(true);
    }

    b2Shape::Type typeA = contact->GetFixtureA()->GetType();
    b2Shape::Type typeB = contact->GetFixtureB()->GetType();

    b2Assert(0 <= typeA && typeB < b2Shape::e_typeCount);
    b2Assert(0 <= typeA && typeB < b2Shape::e_typeCount);

    b2ContactDestroyFcn* destroyFcn = s_registers[typeA][typeB].destroyFcn;
    destroyFcn(contact, allocator);
}

b2Contact::b2Contact(b2Fixture* fA, int32 indexA, b2Fixture* fB, int32 indexB)
{
    m_flags = e_enabledFlag;

    m_fixtureA = fA;
    m_fixtureB = fB;

    m_indexA = indexA;
    m_indexB = indexB;

    m_manifold.pointCount = 0;

    m_prev = NULL;
    m_next = NULL;

    m_nodeA.contact = NULL;
    m_nodeA.prev = NULL;
    m_nodeA.next = NULL;
    m_nodeA.other = NULL;

    m_nodeB.contact = NULL;
    m_nodeB.prev = NULL;
    m_nodeB.next = NULL;
    m_nodeB.other = NULL;

    m_toiCount = 0;

    m_friction = b2MixFriction(m_fixtureA->m_friction, m_fixtureB->m_friction);
    m_restitution = b2MixRestitution(m_fixtureA->m_restitution, m_fixtureB->m_restitution);
}

// Update the contact manifold and touching status.
// Note: do not assume the fixture AABBs are overlapping or are valid.
void b2Contact::Update(b2ContactListener* listener)
{
    b2Manifold oldManifold = m_manifold;

    // Re-enable this contact.
    m_flags |= e_enabledFlag;

    bool touching = false;
    bool wasTouching = (m_flags & e_touchingFlag) == e_touchingFlag;

    bool sensorA = m_fixtureA->IsSensor();
    bool sensorB = m_fixtureB->IsSensor();
    bool sensor = sensorA || sensorB;

    b2Body* bodyA = m_fixtureA->GetBody();
    b2Body* bodyB = m_fixtureB->GetBody();
    const b2Transform& xfA = bodyA->GetTransform();
    const b2Transform& xfB = bodyB->GetTransform();

    // Is this contact a sensor?
    if (sensor)
    {
        const b2Shape* shapeA = m_fixtureA->GetShape();
        const b2Shape* shapeB = m_fixtureB->GetShape();
        touching = b2TestOverlap(shapeA, m_indexA, shapeB, m_indexB, xfA, xfB);

        // Sensors don't generate manifolds.
        m_manifold.pointCount = 0;
    }
    else
    {
        Evaluate(&m_manifold, xfA, xfB);
        touching = m_manifold.pointCount > 0;

        // Match old contact ids to new contact ids and copy the
        // stored impulses to warm start the solver.
        for (int32 i = 0; i < m_manifold.pointCount; ++i)
        {
            b2ManifoldPoint* mp2 = m_manifold.points + i;
            mp2->normalImpulse = 0.0f;
            mp2->tangentImpulse = 0.0f;
            b2ContactID id2 = mp2->id;

            for (int32 j = 0; j < oldManifold.pointCount; ++j)
            {
                b2ManifoldPoint* mp1 = oldManifold.points + j;

                if (mp1->id.key == id2.key)
                {
                    mp2->normalImpulse = mp1->normalImpulse;
                    mp2->tangentImpulse = mp1->tangentImpulse;
                    break;
                }
            }
        }

        if (touching != wasTouching)
        {
            bodyA->SetAwake(true);
            bodyB->SetAwake(true);
        }
    }

    if (touching)
    {
        m_flags |= e_touchingFlag;
    }
    else
    {
        m_flags &= ~e_touchingFlag;
    }

    if (wasTouching == false && touching == true && listener)
    {
        listener->BeginContact(this);
    }

    if (wasTouching == true && touching == false && listener)
    {
        listener->EndContact(this);
    }

    if (sensor == false && touching && listener)
    {
        listener->PreSolve(this, &oldManifold);
    }
}
